1. Field of the Invention
The present invention relates to sheet material deformation correcting method, cutting method, deformation correcting apparatus and cutting apparatus for correcting a deformation such as a curl of a rolled sheet material and for cutting the rolled sheet material.
2. Description of the Related Art
Generally, the various image recording carriers (or sheet materials) such as photographic photosensitive material, heat-sensitive sheets of paper or pressure-sensitive sheets of paper having polymer supports (or polymer sheet materials) are formed, for example, by applying a recording layer (or photographic emulsion layer) to the support. This support is made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or polyethylene laminate paper, a triacetate cellulose film, a polyester film, or the like.
The aforementioned image recording carrier or paper material is usually manufactured as a web and is employed as a rolled film. Therefore, the image recording carrier is aged by the rolled state to curl the support so that this curled state is left in the image recording carrier after the carrier is cut to sheets. This raises a problem that the transferability and stackability of the image recording carrier sheets are seriously deteriorated. When the image recording carrier sheet is treated by various machines such as a developer or printer, moreover, its transfer or image formation is so troubled that it cannot be subjected to a desired treatment. As the case may be, the existence of the curl after the image formation may cause a problem in the quality.
In order to eliminate the curl of this kind, therefore, there have been made a variety of proposals. In Japanese laid-open patent publication No. 51-16358 (as will be called the “Prior Art 1”), there is disclosed a method, by which the polymer film is heated for 0.1 to 1,500 hrs. within a temperature range lower by 30 to 5° C. than the middle point of the glass transition temperature range of the film or the glass transition temperature (Tg) relating to the endothermic maximum.
In Japanese laid-open patent publication No. 62-31653 (as will be called the “Prior Art 2”), on the other hand, there is disclosed a decurl method, by which a rolled photographic photosensitive material is heated and then cooled. Specifically, the photographic photosensitive material is heated at a heating temperature of its melting point or lower (50 to 100° C.) for 2 to 20 secs. and is then cooled down at a temperature lower by 15° C. or more than that heating temperature.
In the aforementioned Prior Art 1, however, the polymer film is heated at the temperature lower than 30 to 5° C. than its Tg. For the practical decurl operation, it takes a considerably long heating time. As a result, the decurl treatment is not efficient to cause problems that the stock loss of the film occurs, and that the facilities become large-sized. Still the worse, the elongated heating time may deteriorate the image characteristics of the recording layer.
In the aforementioned Prior Art 2, on the other hand, the heating temperature rises to a considerably high level. If the heating treatment for the time period as long as 2 to 20 secs. is performed at such high temperature, the image recording layer is affected to raise a problem that the image characteristics are seriously deteriorated. Moreover, though the cooling temperature is defined relative to the heating temperature, the photosensitive material may be cooled at a temperature higher than the glass transition temperature of the support. As a result, the photosensitive material is frequently curled by the handling after the cooling treatment.
In the Prior Art 2, moreover, the heating conditions are individually set according to the materials of the supports so that the recording layer of the photographic photosensitive material cannot be properly matched when it has a different kind. If the kind of the recording layer is different, specifically, the heat resistance is different. Depending upon the kind, therefore, there is pointed out a problem that the quality is troubled by the thermal fogging, the color tone fluctuation, the crack, or the like. According to the change in the processing rate, moreover, the heating conditions may change to make the calorie short or excessive. Thus, there are various problems that the desired decurl effect cannot be obtained, and that the quality is degraded.
For example, in Japanese laid-open patent publication No. 60-2559 (as will be called the “Prior Art 3”), on the other hand, there is disclosed a roll paper decurl apparatus which includes: a correcting member for bending the roll paper rolled on a core, backward of its rolling direction; and heating means for heating the roll paper bent by the correcting member. This heating means is equipped with a fan to be driven by a motor, and a heater for heating the air blown from the fan. On the basis of the information such as the diameter or quality of the roll paper, there is calculated the curl extent, according to which the speed of the motor and the calorific value of the heater are controlled.
In the aforementioned Prior Art 3, however, it is extremely difficult to control the temperature or flow of the hot wind highly responsively and precisely according to the curl of the roll paper, as sequentially changed with the remainder or the like of the roll paper. Thus, there has been pointed out a problem that the desired decurl effect cannot be reliably obtained for the roll paper. Depending upon the kind, moreover, the rolled sheet material to be decurled may be troubled in its quality by the overheat.
In Japanese laid-open patent publication No. 6-64808 (as will be called the “Prior Art 4”), still moreover, a rotatable semicircular shaft is used so that its radially smaller shaft portion may come into abutment against a work (or sheet material) to decurl the work, when the work is fed, and so that its radially larger shaft portion may come into abutment against the work to prevent the work from being curled backward when the work is stopped. By switching the decurl means as the line is run and stopped, specifically, the work is prevented from being curled backward (or back-curled).
In the decurl apparatus, however, the working rate may be changed for the kinds of works or may be frequently increased/decreased or stopped in a repeated manner. There is pointed out a problem that the aforementioned Prior Art 4 cannot be applied to the apparatus of this kind. This is because the change in the working rate will change the curl-removing (or decurl) effect so that the desired decurl treatment cannot be efficiently effected.
On the other hand, there have been widely performed the operations, in which a support web is unwinded from a polymer support (as will be called the “rolled support”) in a rolled shape and in which a recording layer (or photographic emulsion layer) is applied to the support web and is then rolled again. In the rolled support of this kind, there will easily occur the so-called “cut end mark” phenomenon, in which the portion in the vicinity of the core is deformed over several turns by the aging of the rolled support. This cut end mark phenomenon affects the aforementioned step of applying the recording layer thereby to raise a problem that a coating unevenness of the recording layer is caused to deteriorate the quality. At the working step, therefore, the several turns in the vicinity of the roll core are generally dumped to raise a disadvantage that the production yield drops to an uneconomical level.
As disclosed in Japanese laid-open patent publication No. 8-142209 (as will be called the “Prior Art 5”), for example, there is known a flatness improving method for a thermoplastic film. In this method, a film web is guided to pass continuously through: a roller heating step of flattening the film web by transferring and heating it with an infrared ray heater and a heating roller; and a roller cooling step of solidifying the film web, just after heated, by transferring and cooling it by a cooling roller. Moreover, the infrared ray heater of the roller heating step is widthwise divided so that its divided portions are individually set to different temperatures according to the flatness of the film.
In the aforementioned Prior Art 5, however, the heating conditions for the film are hard to promptly change when the material or thickness of the film changes, when the film velocity including the acceleration/deceleration changes or when the line is stopped. As a result, the film may be over-heated and elongated.
When especially a thermal imaging material such as a thermal imaging photosensitive material is to be cut, there is adopted a method for snipping the material with an upper blade and a lower blade. Since the image forming layer (such as a photosensitive layer or a heat-sensitive layer) of the thermal imaging material is thick and fragile, however, there will easily arise degradations such as the film separation, the crack and the separation from the film base by the cutting action. As a result, there is a problem that the image forming layer is degraded.
Against these problems, there have been adopted in the prior art the methods of: adjusting the edge angle one (mainly the upper one) of the upper blade and the lower blade; adjusting the fine shape of the edge, adjusting the relative positions and the cutting angles such as the gap, the snipping angle and the intersection angle between the upper blade and the lower blade; adjusting imposing force; lowering the cutting speed, etc.
However, the adjustment of the-shapes or the snipping angle of the upper blade and the lower blade of the prior art is defective in that it cannot solve the problems of the film separation, the crack and the peel from the film base by the cutting operations. On the other hand, the adjustments of the shapes and the snipping angle of the upper blade and the lower blade are so delicate that they are difficult to maintain.
Here, the method of cutting the elongated crystal film, the prepreg material and the metallic material is disclosed in Japanese laid-open patent publication No. 9-85680, Japanese patent publication No. 7-90512 and Japanese laid-open patent publication No. 5-111898, in which the material is heated when cut.
In the thermal imaging material to be cut by the invention, however, the image forming layer (or applied film) is laminated over the base layer to form a multi-layered film so that the application thickness of the image forming layer grows thick but fragile. At the time of cutting the thermal imaging material, therefore, there will easily arise a trouble that the surface film peels in a beard shape, comes out as chips or cracks in the image forming layer.
Specifically, as shown in FIG. 64, a thermal imaging material 1 is composed of a base layer 2 and an image forming layer 3 having a photosensitive layer or a heat-sensitive layer. When this thermal imaging material 1 is to be cross-cut, moreover, there has been pointed out a problem that beard-shaped peels 4 or surface cracks 5 occur, on the side cut by the upper blade, on the surface layer of the image forming layer 3 whereas cracks 6 occur, on the side cut by the lower blade, in the image forming layer 3.
As shown in FIG. 65, on the other hand, there is another problem that when the thermal imaging material 1 is to be slit, there is a problem that a banking 7 occurs, on the side cut by the upper blade, on the image forming layer whereas a crack 8 occurs, on the side cut by the lower blade, in the image forming layer 3.